RF Switch with Compensation and Gate Bootstrapping

ABSTRACT

A radio frequency switch device includes a first transistor and a second transistor; a compensation network coupled between a body terminal of the first transistor and a source/drain terminal of the second transistor; and a bootstrapping network having a first terminal coupled to a first bias terminal, a second terminal coupled to a gate terminal of the first transistor, and a third terminal coupled to the body terminal of the first transistor, wherein the bootstrapping network establishes a low impedance path between the gate terminal and the body terminal of the first transistor in response to a first voltage value of the first bias terminal, and wherein the bootstrapping network establishes a high impedance path between the gate terminal and the body terminal of the first transistor in response to a second voltage value of the first bias terminal.

TECHNICAL FIELD

The present invention relates generally to a radio-frequency switch withleakage compensation and gate bootstrapping, and an associated method.

BACKGROUND

High voltage (HV) radio-frequency (RF) switches are known in the art andare typically implemented as stacked MOSFET devices on a siliconsubstrate. HV RF switches can be used as antenna tuning switchableelements, such as HV antenna tuning switches and tunable passivecomponents. HV RF switches can be used in cellular handheld devices totune the impedance and radiation properties of compact antennas. The HVRF switches are attached between the feed or aperture points of anantenna and ground plane via external surface-mount device (SMD)capacitors or inductors. Another application of the HV RF switches is asantenna switches for cellular base stations, where the switches may bestressed with RF voltages exceeding 100 V.

A typical challenge in antenna tuning switch design is to achieve highvoltage handling at RF frequencies, reaching values of 80 V peak (forcellular user equipment) and above 100 V (for cellular base stationequipment), while otherwise sustaining the same performance as at low RFvoltages.

SUMMARY

According to an embodiment, a radio frequency (RF) switch deviceincludes a first transistor and a second transistor, wherein the firstand second transistors are coupled in series at a first source/drainterminal of the second transistor to establish a switchable RF path; afirst compensation network coupled between a body terminal of the firsttransistor and a second source/drain terminal of the second transistor,wherein the first compensation network is configured to establish a pathfor current flowing between the body terminal of the first transistorand the second source/drain terminal of the second transistor in a firstdirection and to block current flowing therebetween in a seconddirection opposite to the first direction; and a first bootstrappingnetwork having a first terminal coupled to a first bias terminal, asecond terminal coupled to a gate terminal of the first transistor, anda third terminal coupled to the body terminal of the first transistor,wherein the first bootstrapping network is configured to establish a lowimpedance path between the gate terminal and the body terminal of thefirst transistor in response to a first voltage value of the first biasterminal, and wherein the first bootstrapping network is configured toestablish a high impedance path between the gate terminal and the bodyterminal of the first transistor in response to a second voltage valueof the first bias terminal.

According to an embodiment, a radio frequency (RF) switch deviceincludes a first transistor and a second transistor, wherein the firstand second transistors are coupled in series at a first source/drainterminal of the second transistor to establish a switchable RF path; afirst compensation network coupled between a body terminal of the firsttransistor and a second source/drain terminal of the second transistor,wherein the first compensation network is configured to establish a pathfor current flowing between the body terminal of the first transistorand the second source/drain terminal of the second transistor in a firstdirection and to block current flowing therebetween in a seconddirection opposite to the first direction; and a first bootstrappingnetwork having a first terminal coupled to a first bias terminal, asecond terminal coupled to a gate terminal of the first transistor, anda third terminal coupled to an internal node of the first compensationnetwork, wherein the first bootstrapping network is configured toestablish a low impedance path between the gate terminal and the bodyterminal of the first transistor in response to a first voltage value ofthe first bias terminal, and wherein the first bootstrapping network isconfigured to establish a high impedance path between the gate terminaland the body terminal of the first transistor in response to a secondvoltage value of the first bias terminal.

According to embodiment, a method of compensating a radio frequency (RF)switch device including a first transistor and a second transistorforming a switchable current path, the method including causing a firstcurrent to flow between a body terminal of the first transistor and adrain terminal of the second transistor in a first direction and causinga second current to flow therebetween in a second direction opposite tothe first direction, wherein the first current is larger than the secondcurrent; establishing a low impedance path between a gate terminal andthe body terminal of the first transistor during an OFF mode ofoperation of the RF switch device; and establishing a high impedancepath between the gate terminal and the body terminal of the firsttransistor during an ON mode of operation of the RF switch device.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of an exemplary RF switch having a firstbias network;

FIG. 2 is a schematic diagram of an exemplary RF switch having a secondbias network;

FIG. 3 is a schematic diagram of the exemplary RF switch of FIG. 1showing leakage currents generated in response to an applied high RFvoltage;

FIG. 4 is a schematic diagram of an exemplary RF switch includingleakage compensation;

FIG. 5 is a schematic diagram of an RF switch including leakagecompensation and gate bootstrapping according to an embodiment;

FIG. 6 is a schematic diagram of a stacked RF switch having a first biasnetwork;

FIG. 7 is a schematic diagram of a stacked RF switch having a secondbias network;

FIG. 8A is a graph of DC voltage components of the stacked RF switch ofFIG. 6 for a nominal DC operating point;

FIG. 8B is a graph of DC voltage components of the stacked RF switch ofFIG. 6 with a large RF signal applied with no leakage currentcompensation and no gate bootstrapping;

FIG. 8C is a graph of DC voltage components of the stacked RF switch ofFIG. 6 with a large RF signal applied having leakage currentcompensation but no gate bootstrapping;

FIG. 8D is a graph of DC voltage components of the stacked RF switch ofFIG. 6 with a large RF signal applied having both leakage currentcompensation and gate bootstrapping, according to an embodiment;

FIG. 8E is a graph of DC voltage components of the stacked RF switch ofFIG. 7 for a nominal DC operating point;

FIG. 8F is a graph of DC voltage components of the stacked RF switch ofFIG. 7 with a large RF signal applied with no leakage currentcompensation and no gate bootstrapping;

FIG. 8G is a graph of DC voltage components of the stacked RF switch ofFIG. 7 with a large RF signal applied having leakage currentcompensation but no gate bootstrapping;

FIG. 8H is a graph of DC voltage components of the stacked RF switch ofFIG. 7 with a large RF signal applied having both leakage currentcompensation and gate bootstrapping, according to an embodiment;

FIG. 9A is an example of a gate bootstrapping network, according to anembodiment;

FIG. 9B is an example of a single transistor gate bootstrapping network,according to an embodiment;

FIG. 9C is an example of a dual transistor gate bootstrapping network,according to an embodiment;

FIG. 10 is a schematic diagram of an RF switch including leakagecompensation and gate bootstrapping according to another embodiment; and

FIG. 11 is a block diagram of a bootstrapping method for an RF switchaccording to an embodiment.

FIG. 12A is a schematic diagram of an RF switch having a singleswitchable path, and an equivalent RF switch having two parallelswitchable paths;

FIG. 12B is a schematic diagram of an example gate bootstrapping networkthat can be used with either of the RF switches shown in FIG. 12A;

FIG. 12C is a schematic diagram of an example first compensation networkthat can be used with either of the RF switches shown in FIG. 12A; and

FIG. 12D is a schematic diagram of an example second compensationnetwork that can be used with either of the RF switches shown in FIG.12A.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the presently preferred embodiments arediscussed in detail below. It should be appreciated, however, that thepresent invention provides many applicable inventive concepts that canbe embodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the invention, and do not limit the scope of the invention.

The high voltage handling of HV RF switches at RF frequencies can beimproved through the use of compensation circuits for compensatingleakage currents present during an OFF mode of operation, which maycompromise high voltage handling performance. HV RF switch compensationcircuits are described in U.S. Pat. Nos. 10,333,510, 10,680,599, and USPatent Application No. 2020/0321957, each of which is herebyincorporated in their entirety. In addition to the action of thecompensation circuits, the high voltage handling of the HV RF switchescan be further improved through the action of a bootstrapping circuit,which is described in further detail below according to embodiments. Thebootstrapping circuit improves high voltage handling performance byestablishing a low impedance path between a gate terminal and the bodyterminal of at least one transistor in the RF switch during an OFF modeof operation of the RF switch, and establishing a high impedance pathbetween the gate terminal and the body terminal of the at least onetransistor during an ON mode of operation of the RF switch device. Thelow impedance path between the gate terminal and the body terminaladvantageously improves biasing conditions of the RF switch in order towithstand even higher voltages during the OFF mode of operation, and thecorresponding high impedance path between the gate terminal and the bodyterminal does not adversely affect switch performance during the ON modeoperation of the RF switch.

An RF switch arrangement typically comprises a stacked arrangement of aplurality of MOS transistors since the extremely high voltagerequirements of the RF switch arrangement far exceed the voltagehandling capability of any individual MOS transistor in the stack. Thetotal number of transistors in the stack is determined by the maximumvoltage handling capability desired divided by the maximum voltagehandling capability of an individual MOS transistor. Typically, ten ormore MOS transistors are used in embodiments, but the exact number oftransistors used can vary in different applications.

An individual MOS transistor used in RF switch arrangements comprises agate terminal, a source terminal, a drain terminal and a body terminal.For proper operation, the MOS transistor is biased to the desiredoperating point by means of high-ohmic linear resistors. High-resistiveDC path is provided for all terminals, including gate, source, drain andbody terminals. After applying target DC voltages at each terminal viahigh-ohmic bias resistors the gate-source, gate-drain, drain-body andsource-body voltages define the operating point of the MOS transistor inthe switch arrangement, with the gate-source voltage and the gate-drainvoltage being particularly important in defining the desired operatingpoint of the MOS transistor.

An example of an RF switch arrangement with two MOS transistors and thebias network thereof is shown in FIG. 1 and FIG. 2. For simplicity onlytwo MOS transistors out of the full plurality of MOS transistors areshown. Various other possible arrangements of the bias networks shown inFIG. 1 and FIG. 2 are known in the art.

In FIG. 1, exemplary RF switch arrangement 100 includes a first MOStransistor M₁ having a gate terminal 102A, a source terminal 104A, adrain terminal 106A, and a body terminal 108A, and a second MOStransistor M₂ having a gate terminal 102B, a source terminal 104B, adrain terminal 106B, and a body terminal 108B. The source terminal 104Bof transistor M₂ is coupled to the drain terminal 106A of transistor M₁in exemplary RF switch arrangement 100. High-ohmic resistors are coupledbetween the gate, source-drain and body terminals of respectivetransistors in the stack and the corresponding bias DC voltages V_(g),V_(b), and V_(s), as shown in FIG. 1. For example, for transistor M₁,high-ohmic resistor R_(g1) is coupled between DC bias voltage V_(g) andgate terminal 102A and high-ohmic resistor R_(b1) is coupled between DCbias voltage V_(b) and body terminal 108A. For transistor M₂, high-ohmicresistor R_(g2) is coupled between DC bias voltage V_(g) and gateterminal 102B and high-ohmic resistor R_(b2) is coupled between DC biasvoltage V_(b) and body terminal 108B. Finally, a high-ohmic resistorR_(s1) is coupled to the drain terminal 106A of transistor M₁ and thesource terminal 104B of transistor M₂.

In FIG. 2, exemplary RF switch arrangement 200 also includes a first MOStransistor M₁ having a gate terminal 102A, a source terminal 104A, adrain terminal 106A, and a body terminal 108A, and a second MOStransistor M₂ having a gate terminal 102B, a source terminal 104B, adrain terminal 106B, and a body terminal 108B. The source terminal 104Bof transistor M₂ is also coupled to the drain terminal 106A oftransistor M₁ in exemplary RF switch arrangement 200. High-ohmicresistors are coupled between the gate, source-drain and body nodes ofrespective transistors in the stack, forming a series chain of biasresistors tapped to bias voltages at one or multiple points along thechain, as shown in FIG. 2. For example, high-ohmic resistor R_(gg1) iscoupled between the gate terminal 102A of transistor M₁ and the gateterminal 102B of transistor M₂, and high-ohmic resistor R_(gc) iscoupled between DC bias voltage V_(g) and the gate terminal 102A oftransistor M₁. High-ohmic resistor R_(bb1) is coupled between the bodyterminal 108A of transistor M₁ and the body terminal 108B of transistorM₂, and high-ohmic resistor R_(bc) is coupled between DC bias voltageV_(b) and the body terminal 108A of transistor M₁. Finally, a high-ohmicresistor R_(sd1) is coupled between the source terminal 104A oftransistor M₁ and the drain terminal 106A of transistor M₁, a high-ohmicresistor R_(sd2) is coupled between the source terminal 104B oftransistor M₂ and the drain terminal 106B of transistor M₂, and ahigh-ohmic resistor R_(sdc) is coupled between DC bias voltage V_(s) andthe source terminal 104A of transistor M₁.

In addition to the RF switch arrangements shown in FIG. 1 and FIG. 2,any combination thereof can also be used in a single RF switch,according to embodiments. Also, in addition to the RF switcharrangements shown in FIG. 1 and FIG. 2, any combination thereof canalso be used in a single RF switch, where V_(b) and/or V_(s) arefeedback-regulated bias voltages according to embodiments described inU.S. Pat. No. 10,333,510.

The RF switch arrangements shown in FIG. 1 and FIG. 2 provide a highimpedance r_(sd1) at source-drain nodes and r_(b1) at body nodes, withpossibly different absolute values for r_(sd1) and r_(b1) for eacharrangement.

FIG. 3 is a schematic diagram of the exemplary RF switch arrangement 100of FIG. 1 showing leakage currents generated in response to an appliedhigh RF voltage. When the RF switch arrangement 100 of FIG. 3 is exposedto high peak voltages at RF frequencies (defined as the peak voltage atwhich the voltage drop across each individual transistor M₁ and M₂ inthe stack of MOS transistors approaches a maximum allowable level for agiven MOS transistor type), parasitic leakage currents i_(leakd) andi_(leaks) begin flowing from drain and source terminals into the bodyterminals of the respective MOS transistor in the RF switch arrangement100. These leakage currents shift the operating point of MOS transistorsM₁ and M₂ when flowing into respective high-ohmic bias resistors R_(b1),R_(b2), and R_(s1) is shown by the following equations:

the drain voltage of MOS transistor M₁ and source voltage of MOStransistor M₂ is shifted by the value ofΔV_(rs1)=R_(s1)(i_(leakd)+i_(leaks)); the body voltage of MOS transistorM₁ is shifted by the value of ΔV_(rb1)=R_(b1)(i_(leakd)+i_(leaks)); thebody voltage of MOS transistor M₂ is shifted by a value equal toΔV_(rb1) if the value of resistor R_(b1) is equal to the value ofresistor R_(b2); and the gate voltage of MOS transistors M₁ and M₂remains unchanged as there is no current flowing through the gate oxidethrough high-ohmic resistors R_(g1) and R_(g2).

Such change in DC voltages at the terminals of the switch transistor maysomewhat limit maximum voltage handling capability, primarily becausethe gate-source DC voltage becomes less negative along the stack of theRF switch arrangement.

Solutions for the compensation of operating point shift at high RFvoltages due to leakage current are known in the art. For example, inU.S. Pat. No. 10,333,510 the RF switch arrangement comprisesdynamically-adjustable bias DC voltages V_(s) and/or V_(b). The leakagecurrent into the source and drain terminals of the MOS RF switchtransistor is sensed, the bias voltage V_(s) and/or V_(b) at high-ohmicbiasing resistor is adjusted to keep MOS RF switch transistor in thedesired operating point. Another solution for the compensation ofoperating point shift at high RF voltages due to leakage current isdescribed in U.S. Pat. No. 10,680,599. The compensation described inU.S. Pat. No. 10,680,599 is referred to herein as Gate-Induced DrainLeakage (GIDL) compensation. A nonlinear compensation circuit is addedbetween the drain terminal of each transistor in the stack of the RFswitch arrangement and the body terminal of the adjacent transistor inthe stack of the RF switch arrangement as is shown in FIG. 4.

FIG. 4 is a schematic diagram of an exemplary RF switch 400 includingGIDL leakage compensation including a stack of MOS transistors M₁ andM₂, wherein the drain of MOS transistor M₁ is coupled to the source ofMOS transistor M₂. Exemplary RF switch 400 shows a first nonlinearcompensation network 402 coupled between the drain terminal of MOStransistor M₂ and the body terminal of transistor M₁. Exemplary RFswitch 400 also shows a second nonlinear compensation network 404coupled between the source terminal of MOS transistor M₁ and the bodyterminal of transistor M₂. The nonlinearity function of the twononlinear compensation circuits is the same between a body terminal anda source or drain terminal of the adjacent transistor in the stack as isshown in FIG. 4. Other combinations of nonlinear compensation circuitsare described in U.S. Pat. No. 10,680,599.

This GIDL compensation circuits shown in FIG. 4 may stabilize theoperating point of MOS transistors in an RF switch at high drive levels.However, in some applications it may also tend to over compensate theoperating point of the MOS transistors, making the body voltage morenegative and the drain/source voltages more positive than in the nominaloperating point, where no RF signal is applied to the switch. The GIDLcompensation circuit shown in FIG. 4, in combination with a proposedgate bootstrapping network may advantageously bring further benefits tothe operating point distribution along the switch stack, as will beshown and described below.

According to embodiments, at least one bootstrapping network is added tothe stacked RF switch 400 with GIDL compensation as was shown in FIG. 4and previously described. An RF switch 500 including stackedtransistors, GIDL compensation networks, and two embodimentbootstrapping networks is shown in FIG. 5 and is described in furtherdetail below. Practical implementation of the bootstrapping networkadditionally comprises high-ohmic bias resistor networks around the gateterminal, the source-drain terminals, and the body terminal of thetransistors in the RF switch 500, which are not shown in FIG. 5 forsimplicity.

FIG. 5 thus shows an RF switch 500 including two transistors M₁ and M₂in a stacked configuration, although a practical implementation of RFswitch 500 may include a multiplicity of such stacked MOS transistors,which are not shown in FIG. 5. MOS transistor M₁ includes a gateterminal 502A, a source terminal 504A, a drain terminal 506A, and a bodyterminal 508A, MOS transistor M₂ includes a gate terminal 502B, a sourceterminal 504B, a drain terminal 506B, and a body terminal 508B, and thedrain terminal 506A of MOS transistor M₁ is coupled to the sourceterminal 504B of MOS transistor M₂ in the stacked configuration. RFswitch 500 also includes a first nonlinear compensation network 402coupled between body terminal 508A of MOS transistor M₁ and the drainterminal 506B of MOS transistor M₂, and a second nonlinear compensationnetwork 404 coupled between body terminal 508B of MOS transistor M₂ andthe source terminal 504A of MOS transistor M₁, both of which have beenpreviously described. RF switch 500 also includes a biasing network 516comprising resistors 516A, 516B, 516C, and 516D coupled together inseries fashion. Resistors 516A and 516B are coupled between sourceterminal 504A of MOS transistor M₁ and the drain terminal 506A of MOStransistor M₁, having an intermediate or tap terminal designatedV_(DS1). Resistors 516C and 516D are coupled between source terminal504B of MOS transistor M₂ and the drain terminal 506B of MOS transistorM₂, having an intermediate or tap terminal designated V_(DS2). Finally,RF switch 500 also includes a first bootstrapping network 512 coupledbetween biasing network 516 and MOS transistor M₁, and a secondbootstrapping network 514 coupled between biasing network 516 and MOStransistor M₂, according to an embodiment. The implementation andfunction of the first bootstrapping network 512 and the secondbootstrapping network 514, and the connections to RF switch 500 aredescribed in further detail below.

The circuit that performs the bootstrapping of the gate terminal of anMOS transistor during high voltage operation in the OFF state of RFswitch 500 is described herein as a “bootstrapping network” or “gatebootstrapping network”. The circuit of bootstrapping networks 512 and514 comprises three terminals, “b” for “body terminal, “g” for “gateterminal”, and “sd” for “source/drain” terminal as is shown in FIG. 5.In an embodiment the “b” terminal is coupled to the body of a respectiveswitch transistor, directly or via a resistive element, for example aresistor. In an embodiment the “g” terminal is coupled to the gateterminal of a respective switch transistor, directly or via a resistiveelement. In an embodiment the “sd” terminal is coupled to a tap terminalof a biasing network with a DC voltage ranging between the source anddrain voltages of a respective switch transistor. In other words, the“sd” terminal of the bootstrapping network can be coupled to the sourceterminal and the drain terminal of a respective switch transistor viathe tap terminal of a resistive divider coupled between these terminals.

The function of the bootstrapping network can therefore be describedaccording to the following equation, wherein V_(g) is the gate terminalvoltage of a respective RF switch transistor, V_(b) is the body terminalvoltage of the respect RF switch transistor, and V_(sd) is the voltagebetween the source and drain of the respective RF switch transistor:

$\left\{ {\begin{matrix}{{{low}{impedance}{between}{Vg}{and}{Vb}},{{{if}{Vg}} < {Vsd}}} \\{{{high}{impedance}{between}{Vg}{and}{Vb}},{{{if}{Vg}} \geq {Vsd}}}\end{matrix}.} \right.$

Alternatively, the function of the bootstrapping network may also bedescribed as follows:

$\left\{ {\begin{matrix}{{{low}{impedance}{between}{Vg}{and}{Vb}},{{{if}{Vg}} < {Vsd}}} \\{{{high}{impedance}{between}{Vsd}{and}{Vb}},{{{if}{Vg}} \geq {Vsd}}}\end{matrix}.} \right.$

Alternatively, the function of the bootstrapping network may also bedescribed as follows:

V _(b)≈min {V _(g) , V _(sd)}.

The beneficial effect of gate bootstrapping in a leakage-compensatedswitch according to embodiments is graphically illustrated in FIGS. 8A,8B, 8C, 8D, 8E, 8F, 8G, and 8H for two different RF switch biasconfigurations. The graphs of FIGS. 8A, 8B, 8C, and 8D are associatedwith the stacked RF switch having a first bias network as is shown inFIG. 6. The graphs of FIGS. 8E, 8F, 8G, and 8H are associated with thestacked RF switch having a second bias network as is shown in FIG. 7.The stacked RF switches and graphically illustrated biasing conditionsof the stacked RF switches are described in further detail below.

FIG. 6 is a schematic diagram of a stacked RF switch 600 having a firstbias network. RF switch 600 comprises MOS transistors 602A, 602B, and602C is a stacked configuration. RF switch 600 also comprises an RFsignal source 612 coupled to the drain of MOS transistor 602C through alow value resistor 610. In an embodiment resistor 610 has a value of 50ohms. RF switch 600 also comprises a gate terminal bias voltage sourceV_(g), and a body terminal voltage source V_(b). A first gate biasresistor 604A is coupled between the gate terminal bias voltage sourceV_(g) and the gate terminal of MOS transistor 602A, a second gate biasresistor 604B is coupled between the gate terminal of MOS transistor602A and the gate terminal of MOS transistor 602B, and a third gate biasresistor 604C is coupled between the gate terminal of MOS transistor602B and the gate terminal of MOS transistor 602C. A first source/drainbias resistor 606A is coupled between the source and drain terminals ofMOS transistor 602A, a second source/drain bias resistor 606B is coupledbetween the source and drain terminals of MOS transistor 602B, and athird source/drain bias resistor 606C is coupled between the source anddrain terminals of MOS transistor 602C. A first body bias resistor 608Ais coupled between the body terminal bias voltage source V_(b) and thebody terminal of MOS transistor 602A, a second body bias resistor 608Bis coupled between the body terminal of MOS transistor 602A and the bodyterminal of MOS transistor 602B, and a third body bias resistor 608C iscoupled between the body terminal of MOS transistor 602B and the bodyterminal of MOS transistor 602C. All of the bias resistors shown in FIG.6, except for resistor 610, can comprise high-ohmic bias resistors in anembodiment.

FIG. 7 is a schematic diagram of a stacked RF switch having a secondbias network. RF switch 700 comprises MOS transistors 702A, 702B, and702C is a stacked configuration. RF switch 700 also comprises an RFsignal source 712 coupled to the drain of MOS transistor 702C through alow value resistor 710. In an embodiment resistor 710 has a value of 50ohms. RF switch 700 also comprises a gate terminal bias voltage sourceV_(g), and a body terminal voltage source V_(b). A first gate biasresistor 704A and a second gate bias resistor 704B are coupled betweenthe gate terminal bias voltage source V_(g) and the gate terminal of MOStransistor 702A, a third gate bias resistor 704C is coupled betweeninternal node 704E and the gate terminal of MOS transistor 702B, and afourth gate bias resistor 704D is coupled between internal node 704E andthe gate terminal of MOS transistor 702C. A first source/drain biasresistor 706A is coupled between the source and drain terminals of MOStransistor 702A, a second source/drain bias resistor 706B is coupledbetween the source and drain terminals of MOS transistor 702B, and athird source/drain bias resistor 706C is coupled between the source anddrain terminals of MOS transistor 702C. A first body bias resistor 708Aand second body bias resistor 708B are coupled between the body terminalbias voltage source V_(b) and the body terminal of MOS transistor 702A,a third body bias resistor 708C is coupled between internal node 708Eand the body terminal of MOS transistor 702B, and a fourth body biasresistor 708D is coupled between internal node 708E and the bodyterminal of MOS transistor 702C. All of the bias resistors shown in FIG.7, except for resistor 710, can comprise high-ohmic bias resistors in anembodiment.

DC operating points of RF switch 600 in an OFF mode of operation areshown in the graphs of FIGS. 8A-8D and described below, and DC operatingpoints of RF switch 700 in an OFF mode of operation are shown in thegraphs of FIGS. 8E-8H, wherein the X-axis of each graph represents therank order of a transistor in the corresponding RF switch stack, and theY-axis of each graph represents the value of a DC voltage component ofthe DC operating point.

An important parameter shown in the graphs of FIGS. 8A-8D and 8E-8H formaximizing voltage handling capabilities of the RF switch is thegate-source voltage distribution of a transistor along the stack ofswitch transistors, which primarily defines the operating point (OP) ofthe individual switch transistors. Ideally, the gate-source voltage ofthe switch transistors should be as flat as possible and should be morenegative than the nominal operating point (i.e. OP when no RF signal isapplied).

As can be seen from the graphs of FIGS. 8A-8D and 8E-8H, when no gatebootstrapping is utilized, the OP shift is primarily defined by thedrain/source voltage shift for a high RF drive signal. The gate voltagealways remains constant due to the fact that there is no substantialcurrent flowing into the gate. The body voltage shift does not influencethe gate-source operating point.

According to embodiment concepts, gate bootstrapping takes advantage ofthe beneficial body voltage shift provided by the GIDL compensationcircuit onto the transistors operating point. This is achieved byproviding a low-impedance path between the body and gate such that thegate voltage also reduces when the switch is compensated by the GIDLcompensation circuit. The gate-source operating point is the mostbeneficial with respect to high voltage handling capability of the RFswitch when gate bootstrapping is applied to at least one of thetransistors in the RF switch.

FIG. 8A is a graph of DC voltage components of the stacked RF switch 600of FIG. 6 for a nominal DC operating point, wherein no RF signal isapplied to RF switch 600. Thus, the drain and source voltage 808A of theswitch transistors is at a zero voltage value, and the gate voltage806A, the body voltage 804A, and the gate-source voltage 802A of theswitch transistors is at a linear negative voltage value.

FIG. 8B is a graph of DC voltage components of the stacked RF switch 600of FIG. 6 with a large RF signal applied thereto with no leakage currentcompensation and no gate bootstrapping. The drain and source voltage808B of the switch transistors deviates from a zero voltage value due tothe action of leakage currents, the gate voltage 806B of the switchtransistors is at a linear negative voltage value, the body voltage 804Bof the switch transistors increases from an initial negative value dueto the action of the leakage currents, and the gate-source voltage 802Bof the switch transistors becomes more positive and mirrors the drainand source voltage component due to the action of the leakage currents.

FIG. 8C is a graph of DC voltage components of the stacked RF switch 600of FIG. 6 with a large RF signal applied having leakage currentcompensation but no gate bootstrapping. The drain and source voltage808C of the switch transistors also deviates from a zero voltage valuedue to the action of compensation circuits, the gate voltage 806C of theswitch transistors is at a linear negative voltage value, the bodyvoltage 804C of the switch transistors decreases from an initialnegative value due to the action of the compensation circuits, and thegate-source voltage 802C of the switch transistors becomes more negativeand mirrors the drain and source voltage component due to the action ofthe compensation circuits.

FIG. 8D is a graph of DC voltage components of the stacked RF switch 600of FIG. 6 with a large RF signal applied having both leakage currentcompensation and gate bootstrapping, according to an embodiment. Thedrain and source voltage 808D of the switch transistors also deviatesfrom a zero voltage value due to the action of compensation circuits,the gate voltage 806D of the switch transistors and the body voltage804D of the switch transistors both decrease from an initial negativevalue due to the action of the compensation circuits and gatebootstrapping, and the gate-source voltage 802D of the switchtransistors becomes more negative and mirrors the drain and sourcevoltage component and advantageously becomes more negative than anyother voltage component due to the action of the compensation circuitsand gate bootstrapping.

FIG. 8E is a graph of DC voltage components of the stacked RF switch 700of FIG. 7 for a nominal DC operating point, wherein no RF signal isapplied to RF switch 700. Thus, the drain and source voltage 808E of theswitch transistors is at a zero voltage value, and the gate voltage806E, the body voltage 804E, and the gate-source voltage 802A of theswitch transistors is at a linear negative voltage value.

FIG. 8F is a graph of DC voltage components of the stacked RF switch 700of FIG. 7 with a large RF signal applied thereto with no leakage currentcompensation and no gate bootstrapping. The drain and source voltage808F of the switch transistors deviates from a zero voltage value due tothe action of leakage currents, the gate voltage 806F of the switchtransistors is at a first linear negative voltage value, the bodyvoltage 804F of the switch transistors is at a second linear negativevoltage value, and the gate-source voltage 802F of the switchtransistors becomes more positive and mirrors the drain and sourcevoltage component due to the action of the leakage currents.

FIG. 8G is a graph of DC voltage components of the stacked RF switch 700of FIG. 7 with a large RF signal applied having leakage currentcompensation but no gate bootstrapping. The drain and source voltage808G of the switch transistors also deviates from a zero voltage valuedue to the action of compensation circuits, the gate voltage 806G of theswitch transistors is at a first linear negative voltage value, the bodyvoltage 804G of the switch transistors is at a second linear negativevoltage, and the gate-source voltage 802G of the switch transistorsbecomes more negative and mirrors the drain and source voltage componentdue to the action of the compensation circuits.

FIG. 8H is a graph of DC voltage components of the stacked RF switch 700of FIG. 7 with a large RF signal applied having both leakage currentcompensation and gate bootstrapping, according to an embodiment. Thedrain and source voltage 808H of the switch transistors also deviatesfrom a zero voltage value due to the action of compensation circuits,the gate voltage 806H of the switch transistors and the body voltage804H of the switch transistors are both at a linear negative voltage,and the gate-source voltage 802H of the switch transistors becomes morenegative and mirrors the drain and source voltage component andadvantageously becomes more negative than any other voltage componentdue to the action of the compensation circuits and gate bootstrapping.

The implementation of the bootstrapping network is described below withrespect to FIGS. 9A, 9B, and 9C. According to bootstrapping networkembodiments, a low-ohmic path is created between the gate and body ofeach RF transistor in a stack of an RF switch when the DC gate voltageis less than V_(ds) (indicating that the switch operates on OFF state),and to remove the path, or create a high-ohmic path when the DC gatevoltage is higher than V_(ds) (indicating that the switch operates in ONstate). Alternatively, a low-ohmic path between the body anddrain-source can be established when the switch operates in ON mode.

FIG. 9a shows the symbol for a bootstrapping network 900A including afirst terminal 902A (the “sd” terminal), a second terminal 904A (the “g”terminal), and a third terminal 906A (the “b” terminal), according to anembodiment. The function and terminal names of the bootstrapping networkhave been previously described.

FIG. 9B shows a single-transistor bootstrapping network 900B forimplementing the symbol of FIG. 9A, according to an embodiment.Bootstrapping network 900B comprises a transistor 908 having a gateterminal coupled to the first terminal 902B, a drain terminal coupled tothe second terminal 904B, and a source terminal coupled to the thirdterminal 906B. According to an embodiment, the body terminal oftransistor 908 is coupled to the third terminal 906B.

FIG. 9C shows a two-transistor bootstrapping network 900C forimplementing the symbol of FIG. 9A, according to an embodiment.Bootstrapping network 900C comprises a first transistor 912 having agate terminal coupled to the first terminal 902C, a source terminalcoupled to the second terminal 904C; and a second transistor 910 havinga gate terminal coupled to the second terminal 904C, a source terminalcoupled to the first terminal 902C, wherein a drain of the firsttransistor 912 is coupled to a drain of the second transistor 910. In anembodiment, the coupled drains are coupled to the third terminal 906C.In an embodiment, the body terminal of first transistor 912 and the bodyterminal of second transistor 910 are also coupled to the third terminal906C.

Other embodiment circuits for bootstrapping network 900A can be used forimproving the high-voltage handling capability of an RF switch,including one or more transistors.

Another embodiment of an RF switch 1000 with GIDL compensation and gatebootstrapping is shown in FIG. 10. RF switch 1000 includes the biasnetwork 516, first bootstrapping network 512, second bootstrappingnetwork 514, MOS transistor M₁, and MOS transistor M₂, all as previouslydescribed with respect to RF switch 500 of FIG. 5. However, RF switchincludes a first compensation network 1002, a second compensationnetwork 1004, a first diode 1006, and a second diode 1008. The firstcompensation network 1002 is implemented as a series connection of adiode and a resistor, wherein the “b” terminal of first bootstrappingnetwork 512 is tapped to the internal node 1010 of first compensationnetwork 1002 via a diode 1006. The voltage at the anode of diode 1006 issubstantially the same as the body voltage of transistor M₁, if the samediode type is used as in first compensation network 1002. The secondcompensation network 1004 is also implemented as a series connection ofa diode and a resistor, wherein the “b” terminal of second bootstrappingnetwork 514 is tapped to the internal node 1012 of second compensationnetwork 1004 via a diode 1008. The voltage at the anode of diode 1008 issubstantially the same as the body voltage of transistor M₂ if the samediode type is used as in second compensation network 1004.

FIG. 11 is a block diagram of a bootstrapping method 1100 forcompensating a radio frequency (RF) switch device comprising a firsttransistor and a second transistor forming a switchable current path,the method comprising causing a first current to flow between a bodyterminal of the first transistor and a drain terminal of the secondtransistor in a first direction and causing a second current to flowtherebetween in a second direction opposite to the first direction,wherein the first current is larger than the second current in step1102; establishing a low impedance path between a gate terminal and thebody terminal of the first transistor during an OFF mode of operation ofthe RF switch device in step 1104; and establishing a high impedancepath between the gate terminal and the body terminal of the firsttransistor during an ON mode of operation of the RF switch device instep 1106.

Bootstrapping method 1100 can further comprise causing a third currentto flow between a body terminal of the second transistor and a sourceterminal of the first transistor in step 1108; establishing a lowimpedance path between a gate terminal and the body terminal of thesecond transistor during the OFF mode of operation of the RF switchdevice in step 1110; and establishing a high impedance path between thegate terminal and the body terminal of the second transistor during theON mode of operation of the RF switch device in step 1112.

Referring now to FIGS. 12A, 12B, 12C, and 12D, a parallel-connected RFswitch having one or more compensation circuits and one or morebootstrapping circuits is described according to embodiments.

In an embodiment, an RF switch can be constructed using a parallelconnection of proportionally-scaled devices that is equivalent to thesingle device. For example, a single MOS transistor comprising twosmaller MOS transistors with all respective terminals coupled togethercan be considered as an equivalent implementation of the single MOStransistor. Alternatively, individual transistors that are not directlycoupled together and reside in parallel switchable paths can also beused, as is shown in FIG. 12A and described in further detail below.According to embodiments the parallel connection of the two switchablepaths can be used, wherein the one or more compensations networks andthe one or more bootstrapping networks may be coupled to either one ofthe respective terminals of the individual transistors in each stack oftransistors.

For example, referring to FIG. 12A, if a bootstrapping circuit (notshown in FIG. 12A) is coupled to gate, body, and source terminals{V_(g), V_(b), V_(s)} of transistors in RF switch 1200A, it will operateequivalently if the same bootstrapping circuit is coupled to gate, body,and source terminals {V_(g1), V_(b2), V_(s1)} in RF switch 1200B, gate,body, and source terminals {V_(g2), V_(b2), V_(s1)} in RF switch 1200Bor gate, body, and source terminals {V_(g2), V_(b1), V_(s2)} in RFswitch 1200B or any other similar combination of terminals. The reasonfor equivalent operation between RF switch 1200A and RF switch 1200B isthat DC and AC components of voltages along the two switchable currentpaths of RF switch 1200B at the respective transistor in each stack arethe same.

FIG. 12A is a schematic diagram of an RF switch 1200A having a singleswitchable path, and an equivalent RF switch 1200B having two parallelswitchable paths. The single switchable path in RF switch 1200Acomprises MOS transistors M₁, M₂, M₃, M₄, and M₅ is a stackedconfiguration between switch nodes 1202A and 1204A. The drain terminalV_(d), source terminal V_(s) gate terminal V_(g), and body terminalV_(s) are identified for transistor M₄, but not specifically shown inthe other MOS transistors in the stack for simplicity. A firstswitchable path in RF switch 1200B comprises MOS transistors M_(1A),M_(2A), M_(3A), M_(4A), and M_(5A) is a stacked configuration betweenswitch nodes 1202B and 1204B. The drain terminal V_(d1), source terminalV_(s1), gate terminal V_(g1), and body terminal V_(s1) are identifiedfor transistor M_(4A), but not specifically shown in the other MOStransistors in the stack for simplicity. A second switchable path in RFswitch 1200B comprises MOS transistors M_(1B), M_(2B), M_(3B), M_(4B),and M_(5B) is a stacked configuration between switch nodes 1202B and1204B. The drain terminal V_(d2), source terminal V_(s2), gate terminalV_(g2), and body terminal V_(s2) are identified for transistor M_(4B),but not specifically shown in the other MOS transistors in the stack forsimplicity. In RF switch 1200B, transistors in the first and secondswitchable path having the same rank order may be considered separatetransistors or first and second transistor portions of the sametransistor. For example, although transistors M_(4A) and M_(4B) areshown to have separate transistor terminals and shown as separatetransistors, transistors M_(4A) and M_(4B) may be considered astransistor portions of the same equivalent transistor since the terminalvoltages of each transistor portion is the same.

FIG. 12B is a schematic diagram of an example bootstrapping network 1206that can be used with either of the RF switches 1200A or 1200B shown inFIG. 12A, including a first terminal 121, a second terminal 1214, and athird terminal 1216. The connection of bootstrapping network 1206 with asingle RF switch such as RF switch 1200A has been previously described.The connection of bootstrapping network 1206 with a parallel RF switchsuch as RF switch 1200B is described below. First terminal 1212 iscoupled to a bias network as has been previously described. The secondterminal 1214 is coupled to the gate terminal of a first transistorportion or the gate terminal of a second transistor portion. The thirdterminal 1216 is coupled to the body terminal of a first transistorportion or the body terminal of a second transistor portion.

FIG. 12C is a schematic diagram of an example first compensation network1208 that can be used with either of the RF switches 1200A or 1200Bshown in FIG. 12A, including a first terminal 1220 and a second terminal1218. The connection of first compensation network 1208 with a single RFswitch such as RF switch 1200A has been previously described. Theconnection of first compensation network 1208 is described below. Thefirst terminal 1220 is coupled to the body terminal of a firsttransistor portion or the body terminal of a second transistor portion.The second terminal 1218 is coupled to the drain terminal of a firstadjacent transistor portion or the drain terminal of a second adjacenttransistor portion.

FIG. 12D is a schematic diagram of an example second compensationnetwork 1210 that can be used with either of the RF switches 1200A or1200B shown in FIG. 12A, including a first terminal 1222 and a secondterminal 1224. The connection of second compensation network 1210 with asingle RF switch such as RF switch 1200A has been previously described.The connection of second compensation network 1210 is described below.The first terminal 1222 is coupled to the body terminal of a firsttransistor portion or the body terminal of a second transistor portion.The second terminal 1224 is coupled to the source terminal of a firstadjacent transistor portion or the source terminal of a second adjacenttransistor portion.

Example embodiments of the present invention are summarized here. Otherembodiments can also be understood from the entirety of thespecification and the claims filed herein.

Example 1. A radio frequency (RF) switch device includes a firsttransistor and a second transistor, wherein the first and secondtransistors are coupled in series at a first source/drain terminal ofthe second transistor to establish a switchable RF path; a firstcompensation network coupled between a body terminal of the firsttransistor and a second source/drain terminal of the second transistor,wherein the first compensation network is configured to establish a pathfor current flowing between the body terminal of the first transistorand the second source/drain terminal of the second transistor in a firstdirection and to block current flowing therebetween in a seconddirection opposite to the first direction; and a first bootstrappingnetwork having a first terminal coupled to a first bias terminal, asecond terminal coupled to a gate terminal of the first transistor, anda third terminal coupled to the body terminal of the first transistor,wherein the first bootstrapping network is configured to establish a lowimpedance path between the gate terminal and the body terminal of thefirst transistor in response to a first voltage value of the first biasterminal, and wherein the first bootstrapping network is configured toestablish a high impedance path between the gate terminal and the bodyterminal of the first transistor in response to a second voltage valueof the first bias terminal.

Example 2. The RF switch device of Example 1, wherein the firstbootstrapping network includes a third transistor having a gate terminalcoupled to the first terminal, a drain terminal coupled to the secondterminal, and a source terminal coupled to the third terminal.

Example 3. The RF switch device of any of the above examples, whereinthe first bootstrapping network includes a third transistor having agate terminal coupled to the first terminal, a source terminal coupledto the second terminal; and a fourth transistor having a gate terminalcoupled to the second terminal, a source terminal coupled to the firstterminal, wherein a drain of the third transistor is coupled to a drainof the fourth transistor.

Example 4. The RF switch device of any of the above examples, furtherincluding a resistor divider coupled across a current path of the firsttransistor and coupled to the first bias terminal.

Example 5. The RF switch device of any of the above examples, whereinthe current flowing in the first direction is configured to be less thanor equal to a leakage current associated with the body terminal of thefirst transistor.

Example 6. The RF switch device of any of the above examples, furtherincluding a second compensation network coupled between a body terminalof the second transistor and a source/drain terminal of the firsttransistor; and a second bootstrapping network having a first terminalcoupled to a second bias terminal, a second terminal coupled to a gateterminal of the second transistor, and a third terminal coupled to thebody terminal of the second transistor.

Example 7. The RF switch device of any of the above examples, whereinthe switchable RF path includes a first switchable RF path and a secondswitchable RF path in parallel with the first switchable RF path.

Example 8. The RF switch device of any of the above examples, whereinthe first transistor includes a first transistor portion in the firstswitchable RF path, and a second transistor portion in the secondswitchable RF path.

Example 9. The RF switch device of any of the above examples, whereinthe gate terminal of the first transistor includes a gate terminal ofthe first transistor portion or a gate terminal of the second transistorportion, and wherein the body terminal of the first transistor includesa body terminal of the first transistor portion or a body terminal ofthe second transistor portion.

Example 10. The RF switch device of any of the above examples, whereinthe second transistor includes a first transistor portion in the firstswitchable RF path, and a second transistor portion in the secondswitchable RF path.

Example 11. A radio frequency (RF) switch device including a firsttransistor and a second transistor, wherein the first and secondtransistors are coupled in series at a first source/drain terminal ofthe second transistor to establish a switchable RF path; a firstcompensation network coupled between a body terminal of the firsttransistor and a second source/drain terminal of the second transistor,wherein the first compensation network is configured to establish a pathfor current flowing between the body terminal of the first transistorand the second source/drain terminal of the second transistor in a firstdirection and to block current flowing therebetween in a seconddirection opposite to the first direction; and a first bootstrappingnetwork having a first terminal coupled to a first bias terminal, asecond terminal coupled to a gate terminal of the first transistor, anda third terminal coupled to an internal node of the first compensationnetwork, wherein the first bootstrapping network is configured toestablish a low impedance path between the gate terminal and the bodyterminal of the first transistor in response to a first voltage value ofthe first bias terminal, and wherein the first bootstrapping network isconfigured to establish a high impedance path between the gate terminaland the body terminal of the first transistor in response to a secondvoltage value of the first bias terminal.

Example 12. The RF switch device of Example 11, wherein the thirdterminal is coupled to the internal node of the first compensationnetwork through a diode.

Example 13. The RF switch device of any of the above examples, whereinthe first bootstrapping network includes a third transistor having agate terminal coupled to the first terminal, a drain terminal coupled tothe second terminal, and a source terminal coupled to the thirdterminal.

Example 14. The RF switch device of any of the above examples, whereinthe first bootstrapping network includes a third transistor having agate terminal coupled to the first terminal, a source terminal coupledto the second terminal; and a fourth transistor having a gate terminalcoupled to the second terminal, a source terminal coupled to the firstterminal, wherein a drain of the third transistor is coupled to a drainof the fourth transistor.

Example 15. The RF switch device of any of the above examples, furtherincluding a resistor divider coupled across a current path of the firsttransistor and coupled to the first bias terminal.

Example 16. The RF switch device of any of the above examples, whereinthe current flowing in the first direction is configured to be less thanor equal to a leakage current associated with the body terminal of thefirst transistor.

Example 17. The RF switch device of any of the above examples, furtherincluding a second compensation network coupled between a body terminalof the second transistor and a source/drain terminal of the firsttransistor; and a second bootstrapping network having a first terminalcoupled to a second bias terminal, a second terminal coupled to a gateterminal of the second transistor, and a third terminal coupled to aninternal node of the second compensation network.

Example 18. The RF switch device of any of the above examples, whereinthe third terminal of the second bootstrapping network is coupled to theinternal node of the second compensation network through a diode.

Example 19. According to an embodiment, a method of compensating a radiofrequency (RF) switch device including a first transistor and a secondtransistor forming a switchable current path, wherein the methodincludes causing a first current to flow between a body terminal of thefirst transistor and a drain terminal of the second transistor in afirst direction and causing a second current to flow therebetween in asecond direction opposite to the first direction, wherein the firstcurrent is larger than the second current; establishing a low impedancepath between a gate terminal and the body terminal of the firsttransistor during an OFF mode of operation of the RF switch device; andestablishing a high impedance path between the gate terminal and thebody terminal of the first transistor during an ON mode of operation ofthe RF switch device.

Example 20. The method of Example 19, further including causing a thirdcurrent to flow between a body terminal of the second transistor and asource terminal of the first transistor; establishing a low impedancepath between a gate terminal and the body terminal of the secondtransistor during the OFF mode of operation of the RF switch device; andestablishing a high impedance path between the gate terminal and thebody terminal of the second transistor during the ON mode of operationof the RF switch device.

Example 21. According to an embodiment, a radio frequency (RF) switchdevice includes a first transistor and a second transistor, wherein thefirst and second transistors are coupled in series to establish a firstswitchable RF path; a third transistor and fourth transistor, whereinthe third and fourth transistors are coupled in series to establish asecond switchable RF path in parallel with the first switchable RF path;a first non-linear compensation network coupled between a body terminalof the first transistor and a drain terminal of the second transistor;and a first bootstrapping network having a first terminal coupled to agate terminal of the first transistor or a gate terminal of the thirdtransistor, a second terminal coupled to the body terminal of the firsttransistor or a body terminal of the third transistor, and a thirdterminal coupled to a first bias terminal.

Example 22. The RF switch device of Example 21, wherein the firstbootstrapping network is configured to establish a low impedance path inresponse to a first voltage value of the first bias terminal, andwherein the first bootstrapping network is configured to establish ahigh impedance path in response to a second voltage value of the firstbias terminal.

Example 23. The RF switch device of any of the above examples, furtherincluding a second compensation network coupled between a body terminalof the second transistor and a source terminal of the first transistor.

Example 24. The RF switch device of any of the above examples, furtherincluding a second bootstrapping network having a first terminal coupledto a gate terminal of the second transistor or a gate terminal of thefourth transistor, a second terminal coupled to the body terminal of thesecond transistor or a body terminal of the fourth transistor, and athird terminal coupled to a second bias terminal.

While the invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

In the claims:
 1. A radio frequency (RF) switch device comprising: afirst transistor and a second transistor, wherein the first and secondtransistors are coupled in series at a first source/drain terminal ofthe first transistor and the second transistor to establish a switchableRF path; a first compensation network coupled between a body terminal ofthe first transistor and a second source/drain terminal of the secondtransistor, wherein the first compensation network is configured toestablish a path for current flowing between the body terminal of thefirst transistor and the second source/drain terminal of the secondtransistor in a first direction and to block current flowingtherebetween in a second direction opposite to the first direction; anda first bootstrapping network having a first terminal coupled to thefirst source/drain terminal, a second terminal coupled to a gateterminal of the first transistor, and a third terminal coupled to thebody terminal of the first transistor, wherein the first bootstrappingnetwork is configured to establish a low impedance path between the gateterminal and the body terminal of the first transistor in response to afirst voltage value of the first source/drain terminal, and wherein thefirst bootstrapping network is configured to establish a high impedancepath between the gate terminal and the body terminal of the firsttransistor in response to a second voltage value of the firstsource/drain terminal.
 2. The RF switch device of claim 1, wherein thefirst bootstrapping network comprises a third transistor having a gateterminal coupled to the first terminal, a drain terminal coupled to thesecond terminal, and a source terminal coupled to the third terminal. 3.The RF switch device of claim 1, wherein the first bootstrapping networkcomprises: a third transistor having a gate terminal coupled to thefirst terminal, a source terminal coupled to the second terminal; and afourth transistor having a gate terminal coupled to the second terminal,a source terminal coupled to the first terminal, wherein a drain of thethird transistor is coupled to a drain of the fourth transistor.
 4. TheRF switch device of claim 1, further comprising a resistor dividercoupled across a current path of the first transistor and the secondtransistor.
 5. The RF switch device of claim 1, wherein the currentflowing in the first direction is configured to be less than or equal toa leakage current flowing through the body terminal of the firsttransistor.
 6. The RF switch device of claim 1, further comprising: asecond compensation network coupled between a body terminal of thesecond transistor and a source/drain terminal of the first transistor;and a second bootstrapping network having a first terminal coupled to asecond bias terminal, a second terminal coupled to a gate terminal ofthe second transistor, and a third terminal coupled to the body terminalof the second transistor.
 7. The RF switch device of claim 1, whereinthe switchable RF path comprises a first switchable RF path and a secondswitchable RF path in parallel with the first switchable RF path.
 8. TheRF switch device of claim 7, wherein the first transistor comprises afirst transistor portion in the first switchable RF path, and a secondtransistor portion in the second switchable RF path.
 9. The RF switchdevice of claim 8, wherein the gate terminal of the first transistorcomprises a gate terminal of the first transistor portion or a gateterminal of the second transistor portion, and wherein the body terminalof the first transistor comprises a body terminal of the firsttransistor portion or a body terminal of the second transistor portion.10. The RF switch device of claim 7, wherein the second transistorcomprises a first transistor portion in the first switchable RF path,and a second transistor portion in the second switchable RF path.
 11. Aradio frequency (RF) switch device comprising: a first transistor and asecond transistor, wherein the first and second transistors are coupledin series at a first source/drain terminal of the second transistor toestablish a switchable RF path; a first compensation network coupledbetween a body terminal of the first transistor and a secondsource/drain terminal of the second transistor, wherein the firstcompensation network is configured to establish a path for currentflowing between the body terminal of the first transistor and the secondsource/drain terminal of the second transistor in a first direction andto block current flowing therebetween in a second direction opposite tothe first direction; and a first bootstrapping network having a firstterminal coupled to a first bias terminal, a second terminal coupled toa gate terminal of the first transistor, and a third terminal coupled toan internal node of the first compensation network, wherein the firstbootstrapping network is configured to establish a low impedance pathbetween the gate terminal and the body terminal of the first transistorin response to a first voltage value of the first bias terminal, andwherein the first bootstrapping network is configured to establish ahigh impedance path between the gate terminal and the body terminal ofthe first transistor in response to a second voltage value of the firstbias terminal.
 12. The RF switch device of claim 11, wherein the thirdterminal is coupled to the internal node of the first compensationnetwork through a diode.
 13. The RF switch device of claim 11, whereinthe first bootstrapping network comprises a third transistor having agate terminal coupled to the first terminal, a drain terminal coupled tothe second terminal, and a source terminal coupled to the thirdterminal.
 14. The RF switch device of claim 11, wherein the firstbootstrapping network comprises: a third transistor having a gateterminal coupled to the first terminal, a source terminal coupled to thesecond terminal; and a fourth transistor having a gate terminal coupledto the second terminal, a source terminal coupled to the first terminal,wherein a drain of the third transistor is coupled to a drain of thefourth transistor.
 15. The RF switch device of claim 11, furthercomprising a resistor divider coupled across a current path of the firsttransistor and coupled to the first bias terminal.
 16. The RF switchdevice of claim 11, wherein the current flowing in the first directionis configured to be less than or equal to a leakage current associatedwith the body terminal of the first transistor.
 17. The RF switch deviceof claim 11, further comprising: a second compensation network coupledbetween a body terminal of the second transistor and a source/drainterminal of the first transistor; and a second bootstrapping networkhaving a first terminal coupled to a second bias terminal, a secondterminal coupled to a gate terminal of the second transistor, and athird terminal coupled to an internal node of the second compensationnetwork.
 18. The RF switch device of claim 17, wherein the thirdterminal of the second bootstrapping network is coupled to the internalnode of the second compensation network through a diode.
 19. A method ofcompensating a radio frequency (RF) switch device comprising a firsttransistor and a second transistor forming a switchable current path,the method comprising: causing a first current to flow between a bodyterminal of the first transistor and a drain terminal of the secondtransistor in a first direction and causing a second current to flowtherebetween in a second direction opposite to the first direction,wherein the first current is larger than the second current; using afirst bootstrapping network having a first terminal coupled to a commonterminal of the first transistor and the second transistor, a secondterminal coupled to a gate terminal of the first transistor, and a thirdterminal coupled to the body terminal of the first transistor,establishing a low impedance path between a gate terminal and the bodyterminal of the first transistor during an OFF mode of operation of theRF switch device; and establishing a high impedance path between thegate terminal and the body terminal of the first transistor during an ONmode of operation of the RF switch device.
 20. The method of claim 19,further comprising: causing a third current to flow between a bodyterminal of the second transistor and a source terminal of the firsttransistor; establishing a low impedance path between a gate terminaland the body terminal of the second transistor during the OFF mode ofoperation of the RF switch device; and establishing a high impedancepath between the gate terminal and the body terminal of the secondtransistor during the ON mode of operation of the RF switch device. 21.The RF switch device of claim 1, wherein the first terminal of the firstbootstrapping network is coupled to the first source/drain terminalthrough a resistor.
 22. The method of claim 19, wherein the firstterminal of the first bootstrapping network is coupled to the commonterminal of the first transistor and the second transistor through aresistor.